1. Field of the Invention
The present invention generally relates to conveyance control apparatuses and, more particularly, to a conveyance control apparatus for controlling an operation of a paper conveyance apparatus used for an image forming apparatus such as a copy machine, a printer or a facsimile machine, and also relates to an image forming apparatus having such a conveyance control apparatus.
2. Description of the Related Art
In recent years, in the field of inkjet recording, ink is shifted from a dye-based ink to a pigment-based ink so as to improve light fastness and deterioration with age. Additionally, ink having a high-viscosity has become used. By using a high-viscosity ink, run or bleeding of ink on a record paper decreases drastically. However, when the high-viscosity ink is used, a displacement in landing positions of ink droplets on a recording paper becomes highly visible due to white stripes, black stripes, banding, etc. That is, inaccuracy in landing positions of ink droplets becomes visible. Especially, since the accuracy in landing positions of ink droplets depends on accuracy in a stop position of a recording paper when conveying the recording paper in a sub-scanning direction, it is desired to achieve high-accuracy in conveyance of a recording paper.
Conventionally, in a sub-scanning recording paper conveyance mechanism of an inkjet recording system, it is general to use a conveyance method using a wheel conveyance roller or a conveyance belt. In a feed control in such a conventional conveyance method, a code-wheel is attached to a conveyance roller shaft to detect a rotational position or a rotation speed of the conveyance roller shaft by reading a scale provided on the code-wheel by using an encoder sensor. Then, a feed amount of the recording paper is acquired by computation based on the detected rotational position or rotation speed so as to perform the feed amount control (for example, refer to Patent Document 1).
Patent Document 1: Japanese Laid-Open Patent Application No. 2001-253132
In the conventional paper conveyance control using the above-mentioned code-wheel, accuracy in conveyance of recording papers is influenced by eccentricity, deflection and temperature changes in the code-wheel, eccentricity and deflection in a drive pulley and the code-wheel, and variation in a thickness of a conveyance belt. That is, there is a problem that it is difficult to perform a stop position control of a recording paper with good accuracy due to accumulation of parts accuracy of a conveyance mechanism, influences of accuracy in assembling, or the like.